Preparation of protein concentrates by extracting gluten and water-soluble proteins from a slurry of wheat flour,water,and edible glyceride oil



United States Patent PREPARATION OF PROTEIN CONCENTRATES BY EXTRACTING GLUTEN AND WATER-SOLUBLE PROTEINS FROM A SLURRY OF WHEAT FLOUR, WATER, AND EDIBLE GLYCERIDE OIL David A. Fellers, El Cerrito, Calif., assignor to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed June 8, 1966, Ser. No. 556,823

Int. Cl. A23j 1/12; C07g 7/00 US. Cl. 260-112 3 Claims ABSTRACT OF THE DISCLOSURE Protein concentrates are prepared from wheat flour by the following technique: The flour is slurried with water and an edible gluten-modified agent such as corn oil. The slurry is then centrifuged, yielding a supernatant liquid which contains essentially all the protein from the flour. This liquid may be dried and used as a protein supplement in bread and other foods.

A nonexclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to and has among its objects the provision of novel processes for preparing protein concentrates from wheat fiour. Further objects of the invention will be evident from the following description wherein parts and percentages are by weight unless otherwise specified.

It is well known that wheat flour contains valuable proteins plus various other components, primarily starch. For certain purposes it is desirable to treat the flour to obtain compositions which contain an increased proportion of protein. Such procedures are generally cumbersome because of the tendency of the flour to form sticky masses or doughs when incorporated with water and subjected to such manipulations as centrifugation.

By application of the process of the invention this stickiness problem is obviated with the result that the protein and starch components can be effectively separated.

In a practice of the invention the following procedure is employed:

. A slurry of wheat flour, water, and an edible glutenmodifying agent is prepared. In preparing this slurry, one generally uses about 1 to 3 parts of water per part of flour. A preferred proportion which provides a slurry thin enough for easy handling, yet employs a minimum of water (to reduce the expense of drying the protein concentrate eventually obtained), is 1.5 parts of water per part of flour. The critical component in the slurry is the gluten-modifying agent. This substance exerts the important effect of modifying the wheat protein (gluetn) so that its tendency to form a dough or other sticky material is markedly decreased.

In preparing the slurry, the three components-flour, water, and gluten-modifying agentmay be combined all at once. Alternatively, the other components may be added sequentially to the water. Preferably, where the gluten-modifying agent is a water-soluble material, the

following technique is used: The gluten-modifying agent is dissolved in the water. Then, the flour is incorporated in the resulting solution to form the slurry. Where the gluten-modifying agent is a water-insoluble materialfor example, an edible oil-the following technique is preferred: A part of the flour (for example, A of the total amount) is incorporated with the water, the oil is then stirred in, and finally the remainder of the flour is incorporated into the system.

Having prepared the slurry of water, flour, and glutenmodifying agent, this slurry is then subjected to centrifugation. This causes formation of a system containing plural phases: A dense bottom phase; a supernatant liquid phase; and, in some cases, a sludge phase between the bottom phase and the supernatant liquid phase. The bottom phase contains essentially all the prime star-ch from the flour in almost a pure state. This prime starch phase being in a granular condition, completely free from stickiness, can be readily separated from the remainder of the system, and can be readily processed as by washing with water and drying to prepare a high grade starch for any desired use. Essentially all the protein from the flour is contained in the supernatant liquid, or divided between the supernatant and sludge phases where both are present. Both the supernatant and sludge phases are free from stickiness and gumminess so that they can be readily handled, removed from the starch phase, etc. The supernatant liquid and the combined supernatant and sludge phases where both are present constitute valuable protein concentrates useful for many purposes. Typically, the protein concentrates may be dried and used as a protein supplement in bread and other foods, in mixed animal feeds, etc. Also, the protein concentrates can be used as a base for preparing milk-like beverages.

In accordance with the invention various substances may be employed as the gluten-modifying agent, for example: Water-soluble proteins such as soybean protein, gelatin, sodium caseinate, and substances containing casein, e.g., dried milk; edible (glyceride) oils, such as soybean oil, peanut oil, corn oil, cottonseed oil, safilower oil, olive oil, and the like; water-soluble cellulosic gums such as methyl cellulose and carboxymethyl cellulose; phospholipids such as lecithin and cephalin. These substances may be used individually or as admixtures of two or more. The gluten-modifying agent is operative over a wide range of proportions. Usually, it is preferred to use the minimum effective amount of the agent and generally this will be in the range from about /2 to about 5 parts thereof per parts of flour. Larger proportions may be used-for example, up to 30 parts per 100 parts of flourbut they exert little, if any, extra benefit.

In the process of the invention, essentially all of the added gluten-modifying agent appears in the protein concentrate; that is, it is in the supernatant liquid or divided between the supernatant and sludge layers where both of these phases are present. The occurrence of the additive in the final product is not a detriment because it is an edible material and may even add to the nutritive value of the protein concentrate. This is the case, for example, where the additive is a protein or edible oil. The presence of the edible oil in the protein concentrate is especially desirable where the latter is to be converted into a milk-like beverage of full-fat character in that no extra fat need be added to achieve this end.

Ordinarily, for convenience, the slurry of flour, water, and gluten-modifying agent is prepared at room temperature. However, it has been observed that special benefits are attained at lower temperatures, i.e., the intermediate sludge layer has a more liquid character and is easier to remove from the centrifuge. Accordingly, in a preferred modification of the invention, the slurry is prepared in the cold, that is, at a temperature below room temperature but not so low as to cause the slurry to become frozen. For best results, the temperature is lowered to a point just above freezing, for example, about a degree above 32 P. so that the slurry remains a liquid. The benefit of the lowered temperature is primarily achieved when the slurry is prepared in the cold. However, it is also beneficial to maintain the low temperature when the slurry is centrifuged.

The invention is further demonstrated by the following illustrative examples.

EXAMPLE 1 Wheat flour (1 part) was slurried with 1.5 parts of water. To different lots of the slurry was added corn oil in various proportions (as given below) and the mixtures stirred in a blender for l5 minutes. Each of the slurries, at room temperature, was then centrifuged for 5 minutes at 1000 rpm. In each case, it was observed that the slurry separated into a supernatant liquidous layer and a lower layer of prime starch. The supernatant layer was removed to yield the desired protein concentrate.

The results obtained are tabulated below.

Starch removed, Increase in Corn oil added, percent (dry concentration of percent basis, on protein, percent Run (on wt. of flour) wt. of flour) (dry basis) EXAMPLE 2 The procedure of Example 1 was repeated substituting various other agents for the corn oil. In all cases it was observed that the slurry on centrifugation separated properly into the supernatant liquid and prime starch phases.

The results are summarized in the following table.

mque:

Wheat flour (1 part) was slurried with water (1.5 parts). To different lots of the slurry was added, with stirring, non-fat dry milk solids in various proportions (given below). In one of the runs, nothing was added to provide comparative data. The slurries were then centrifuged for 5 minutes at 1500 rpm. The results are tabulated below:

Amount of non- Increase in dry milk Starch removed, concentration of solids added, percent wheat protein, percent based on dry basis on percent wt. of flour wt. of flour dry basis None added 51 204 .It was further observed that in run 11, the centrifuged material was sticky and gummy so that it was diflicult to separate the starch from the supernatant. In runs 12 and 13 the centrifuged material was in two phases: Prime startch and supernatant liquid. Moreover, in these runs there was no stickiness or gumrniness and the supernatant and starch layers could be separated easily and completely.

A particularly important advantage of the invention is that it yields protein concentrates which contain valuable components which are normally lost in conventional procedures for separating the starch and protein components of wheat flour. This feature of the invention will be evident from the following explanation:

In conventional methods, a dough of flour and water is formed and then subjected to kneading while exposed to sprays of water. In this operation the starch and watersoluble components are washed away, leaving a mass of gluten. Starch is readily recovered from the wash water because it is suspended (not dissolved) therein. Thus, it can easily be segregated by flowing the water over rifiles or the like. However, the substances that are actually dissolved cannot be etfectively recovered because of their soluble character and the large volume of wash water in which they exist. These soluble components include watersoluble proteins, vitamins of the B group, minerals, and sugars. It may be noted that the water-soluble proteins are mostly albumins which are particularly desired from a nutritive standpoint in that they contain a balanced proportion of amino acids. Gluten, in contrast, is deficient in the essential amino acid lysine. It is evident from the above explanation that the conventional procedure yields a protein concentrate, i.e. gluten, which is lacking in the valuble water-soluble components of the flour. In contrast, however, the invention surmounts this deficiency in that the protein concentrates contain all the desired components of the flour, including those of a water-soluble nature, e.g., water-soluble proteins, vitamins, minerals and sugars. Thus in the process of the invention, the centrifugation causes a segregation only of the prime starch; the desired componentsincluding the gluten and the watersoluble proteins, vitamins, minerals, and sugars-are concentrated in the supernatant liquid phase (or in the supernatant and sludge phases, where both are present). Accordingly, the concentrates produced in accordance with the invention constitute compositions of matter not hitherto known and which possess significant advantages over the known concentrates.

Having thus described the invention, what is claimed is:

1. A method for preparing a protein concentrate from wheat flour which comprises (a) preparing a slurry of wheat flour, water and an edible glyceride oil to decrease the tendency of the flour to form a dough, the proportion of water being 1 to 3 parts thereof per part of flour, the proportion of glyceride oil being 0.5 to 30 parts thereof per parts of flour,

(b) centrifuging the slurry to segregate the starch from the proteinous components of the flour, and

(c) removing the segregated starch to obtain a proteinous composition of increased protein concentration.

2. The method of claim 1 wherein the glyceride oil is corn oil.

3. The process of claim 1 wherein the slurry is prepared at a temperature below room temperature but above freezing and held at such temperature until centrifuged.

References Cited UNITED STATES PATENTS 2,455,981 12/1948 Dimlel l27 -67 2,461,829 2/1949 Lowen l06-136 2,516,117 7/1950 Harrel et al. I- 127--67 (Other references on following page) 5 6 2,557,032 6/1951 Kilander 9950 Chem-Abstracts, v01. 27, 1933, 4315(1), Fisher et a1. g g t g; Chem-Abstracts, v01. 53, 1959, 225611, 2256211, Kisaki. ac ana 2,961,353 11/1960 Carlson et a]. n 127 67 Chem Abstracts, vol. 60, 1964, 2252a h, Katsuya et a1. 3,012,888 12/ 1961 Davis et 99-45 5 WILLIAM H, SHORT, Primary Examiner 3,077,407 2/1963 Rozsa et a1. 99-93 3,290,152 12/1966 Hartman 99-17 HOWARD SCHAIN, Assistant Examiner 3,362,829 1/ 1968 Landfiried et a1. 99--14 US. Cl. X.R.

OTHER REFERENCES Chem-Abstracts, v01. 2, 1908 (187,590), Klopfer, 919. -4 17, 7 Chem-Abstracts, v01. 3, 1909 (929,861), Klopfer, 

